An example of such current detection apparatuses, which is disclosed in Japanese Patent Application Publication No. 2017-123736, is applied for a system including an inverter and a rotary electric machine connected to the inverter; the plural pairs of upper- and lower-arm switches correspond to the respective phases of the rotary electric machine.
Specifically, the current detection apparatus, which will be referred to as a conventional current detection apparatus, includes an arm current detector, a bus current detector, and an amplitude correction unit.
The arm current detector detects a peak of each of at least first and second phase currents having respective amplitudes and flowing in the multiphase rotary electric machine based on a potential difference between input and output terminals of the corresponding one of the first and second detection switches while the corresponding one of the first and second detection switches is on.
The bus current detector is configured to detect a peak of a bus current flowing through a bus of the inverter as a bus-based peak for each of the first and second phase currents.
The amplitude correction unit is configured to correct each of the first and second phase currents detected by the arm current detector to thereby match the peak of each of the first and second currents detected by the arm current detector with the bus-based peak for the corresponding one of the first and second phase currents. This results in the amplitudes of the respective first and second phase currents being the same as each other.